Although Mina is right, you can and should do whatever the hell you want to, I have a different opinion on the matter. Now, I for one, am here, at the end of the day, precisely for the freedoms of being able to do things like that. Being able to do whatever I want, when I want, and not answer to anyone.
That being said, this scene is dominated by well to do upper middle class and up. These men want discretion above all. They want to be able to call you to a hotel, and not worry that security will follow you. They want class. Not saying blue, or any other unnatural hair color is trashy by any means, it's just that most guys would have at least a moments more hesitation and forethought about calling you if they had to factor in how you'd be received where ever he's at. Here in Biloxi, you walk into the Beau Rivage with blue hair, and you're going to be stared at hard. Maybe watched... No one wants to think of that when already engaging a call girl. Hard Rock, you'd get ask what brand.. I don't go to the HR often though, and I know most of my clientele prefer knowing that I'm perceived as just a pretty girl walking through to anyone I encounter. It might seem petty, but when a mans entire empire rests on your ability to keep secrets, blending in with crowds is probably your best bet. So, personally, I would recommend against it.
But hell girl, if you want to let your freak flag fly, get some temporary stuff!!! Blue, Neon Pink, Orange, Green... Rock it for the concert, party, week end, or the day, and wash it away! Best of both worlds!